This invention generally relates to methods of manufacturing electronic devices, and more specifically to methods of manufacturing non-linear devices for addressing electronic displays.
Microencapsulated, particle-based displays can be made highly reflective, bistable, and optically and electrically efficient. To obtain a high resolution display, however, individual pixels of a display must be addressable without interference from adjacent pixels. One way to achieve this objective is to provide an array of nonlinear elements, such as transistors, diodes, or varistors, where one or more nonlinear elements are associated with each pixel.
Most examples of nonlinear elements to date have been fabricated using vacuum-deposited silicon on glass. This process is costly in addition to being complex. The complexity prevents large area devices from being readily constructed. In addition, it is difficult to create silicon transistors on plastic or other flexible film.
Recently, there has been significant development in the area of organic semiconducting polymers and molecules. Thin film transistors have been made out of semiconducting polymers. See Bao et al., Soluble and Processable Regioregular Poly(3-hexylthiophene) for Thin Film Field-Effector Transistor Applications with High Mobility, Appl. Phys. Lett. 69(26), 4108 (December 1996); and Bao et al., High-Performance Plastic Transistors Fabricated by Printing Techniques, Chem. Mater. 1997, 9, 1299. U.S. Pat. No. 5,574,291 describes addressing liquid crystal displays with transistors made out of semiconducting polymers. While remarkable advances have been made in the performance of organic-based transistors, the mobility characteristics of many organic semiconductor materials and devices are insufficient to successfully drive many types of liquid crystal or emissive displays. Therefore, many organic-based transistors are not suitable for use with liquid crystal displays.
In addition, liquid crystals can degrade the transistors when they come in contact with the transistors. Many organic semiconductor materials can be swollen by, or dissolved by, liquid crystalline fluids because those fluids are good solvents. This solvent compatibility makes it challenging to design systems in which organic transistor devices can remain stable while in contact with or close proximity to liquid crystalline solvents, limiting their viability.
Many organic-based transistors have been made using a screen printing technology, in which the organic material is squeezed through an opening in a mesh to produce fine lines. Lines having a pitch as small as about 250 microns have been printed using the screen printing technology. While this line spacing is adequate for some applications, it is preferable to construct transistors with much smaller features, a goal not readily reached using screen printing.
In addition, the solvent carrier used for supporting screen printable materials must have a certain range of viscosity and surface energy characteristics. Such solvent carriers can potentially interfere with the electrical characteristics of the semiconductor material of the transistors. Finding proper solvent carriers, therefore, is difficult.
The invention relates to a method of manufacturing an electronic device. In one aspect, an electronic device is manufactured in accordance with the following steps. An ink-jet printing system is provided. The ink-jet printing system includes a print head and a transfer member. A substrate is provided. A plurality of ink drops are dispensed from the print head to a surface of the transfer member forming an ink pattern corresponding to at least a component of the electronic device. The plurality of ink drops can include a conductive material and/or a semiconductive material. The ink pattern is transferred from the transfer member to the substrate, thereby forming the component of the electronic device.
In one embodiment, the ink drops include an organic conductive material and/or an organic semiconductive material. In another embodiment, the ink drops include a colloidal inorganic conductive material and/or a colloidal inorganic semiconductive material, or organometallic material. In one embodiment, the ink drops further includes an insulating material.
In one embodiment, the ink drops form an ink pattern corresponding to at least a component of a transistor, such as a source electrode, a drain electrode, a dielectric layer, a semiconductor layer, or a gate electrode.
In one embodiment, the ink-jet printing system further includes an applicator for applying a release material to the transfer member. For example, the release material can be applied to a surface of the transfer member and the plurality of ink drops can be dispensed adjacent the release material.
In one embodiment, the substrate is provided between the transfer member and a pressure applying member. The substrate can be provided on a conveyor belt. Alternatively, a plurality of substrates can be provided for a batch process. The substrate can be flexible.
In one embodiment, an electronic display media is provided and assembled with the electronic device. The electronic display media can include a plurality of microcapsules, where each capsule includes particles dispersed in a fluid. Alternatively, each microcapsule can include a bichromal sphere.